Circular stitching device for sewing machines



1944- c. A. KI'ESSLER -ET AL 2,359,713

CIRCULAR STITCHING DEVICE FOR SEWING MACHINES Filed Aug. 25 1942 2 Sheets-Sheet l 4 Wmmgwuwvtom Charles A liessler when: Herman Ritt er 3, 1944- c. A. KESSLER ETAL 2,359,713

CIRCULAR STITCHING DEVICE FOR SEWING MACHINES ZSheets-Sheet 2 Filed Aug. 25 1942 Patented Oct. 3, 1944 4 CIRCULAR STITCHING DEVICE FOR SEWING MACHINES Charles A. Kessler, Plainficld', and Herman Ritter,

Cranford, N. J., assignors to The Singer Manufacturing Company, Elizabeth, N. J a corporation of New Jersey Application August 25, 1942, Serial No. 455,980

Claims.

This invention relates to circular stitching devices for sewing machines.

More particularly this invention relates to a work-holding and -guiding device to be employed in a sewing machine in combination with the usual stitching and feeding mechanisms to hold the work fabric so that it will be fed in a circular path about a predetermined center while the stitching instrumentalities apply stitches at a fixed radial distance from and about said center.

A primary object of this invention is to provide an improved work-clamping and guiding means for circular stitching attachments for sewing machines.

A further object of this invention is to provide a novel attachment for a sewing machine for applying stitches in a circular path concentric with a central circular aperture in a work fabric.

Another object of this invention is to provide a circular stitching attachment for a sewing machine having upper and lower work-clamping members readily changeable from a pressuredisk and turntable combination to a spear point and simple work support combination.

A still further object of the invention is to provide a simple, rugged andinexpensive attachment for easily adapting an ordinary sewing machine for stitching in a circular path.

With the above and other objects in view as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a specific embodiment of the invention from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings:

Fig. 1 is a front-side elevational view, partly in section, of a. sewing machine having attached thereto a device embodying the present invention.

Fig. 2 is an end elevational view of the machine shown in Fig. 1. V

Fig. 3 is a horizontal section taken substantially on line 33 of Fig. 1 and showing parts therebelow in plan.

Fig. 4 is a front-side elevational view showing a modified turntable.

Fig. 5 is a front-side elevational view showing a further modification.

Fig. 6 is an enlargedgsectional view of a portion of the device of Fig. 1 showing the work secured therein.

Fig. '7 is an enlarged vertical sectional view taken through the vertical axis of rotation of the 5 modified device of Fig, 4, showing the work secured therein.

Fig. 8 is an enlarged vertical sectional View taken through the vertical axis of rotation of the modified device of Fig. 5, showing the work secured therein.

Referring more particularly to the drawings, Fig. 1 shows the head end of a Singer Class 241 sewing machine, regularly used for straightaway sewing, having the usual presser-bar l and vertically reciprocated needle-bar 2. Secured to the presser-bar by means of screw 3 is the presser-foot A which cooperates with the feed-dog 5 to effect feedingof the work in the usual manner. A needle 6 secured to the needle-bar 2 cooperates with the usual underbed stitch-forming mechanism (not shown) to apply a line of stitches to work material presented to it by the feeding mechanism in accordance with wellknown sewing machine practice.

The presser-footti is formed with a rearwardly-extended shank portion 1 which is provided with a horizontally-disposed slot 8. An angle bracket 9 positioned within said slot 8 is adjustably secured to said presser-foot 4 by a headed screw II] which passes through an elongated slot l l in the bracket and is threaded into the presser-foot. The bracket 9 extends from the presser-foot in a direction away from the machine and transverse to the direction of feed and terminates in a portion I2 which is bent forwardly to stand in a direction parallel to the direction of feed. A block-like body piece I3 is formed with a horizontally-disposed face slot w and is slidingly received on the forwardly bent portion [2 to which said body piece l3 may be adjustably secured by a headed screw I l extending through an elongated slot IS in said bent portion and threaded into the body piece 13.

A pivot-pin l6 formed preferably with a conical point Iii is positioned to slide vertically and freely within the aperture IT in the body piece I3. A bracket-arm I 8, secured to the top side of the body piece I3 by means of screw I9, terminates in a portion which is parallel to and spaced apart from the body piece I3 and is formed with an aperture 20 in register with the body aperture [1 to provide an upper bearing for the pivot-pin IS. A downwardly directed spring bias is applied to the pivot pin I6 by a helical spring 2| which embraces said pin and exerts a force between the bracket-arm l8 and the stop collar 22 adjustably secured to the pivot-pin. This stop collar 22 also limits the downward displacement of the pivot-pin by abutting the upper surface of the body piece [3 after suiiicient displacement thus preventing the pivot-pin from being pulled out of engagement with the bracket aperture 20.

An inverted cup-shaped pressure disk 23, as.

seen best in Fig. 6, is formed with a flanged hub portion 24 connected by integral arms 25*- to an annular rim 26 which presents a plane face portion 26 having a raised annular rib 26 Located on the vertical axis of said disk 23 and within the hub portion 24 is a cylindrical socket or well 21 terminating in a conical bottom 28.

A stiff wire retainer strap 2'9, secured beneath the head of the screw i4 is formed with a vertically depending portion 29 which terminates in a. loop portion 29 disposed in a horizontal plane and loosely embracing the hub portion 24' whereby to retain the pressure disk upon the pivot-pin. The pivot-pin l6 fits loosely within the socket 21, as seen best'in Fig. 6, which permits relative side-play or tilt, and the conical pointed end 16 forms with the conical bottom 28 a pivot-bearing which allows free rotation of the pressure disk relative to the pivot-pin. This construction minimizes the frictional drag torque exerted against the effort of the feeding mechanism to turn the work piece about the pivot point thus preventing distortion of the material and resulting in a more uniform product.

From the above description it is evident that the pressure disk 23 has sufiicient universal movement relative to the pivot-pin I6 to permit its face portion to be seated properly against work surfaces not strictly in -a plane transverse to the axis of said pivot-pin. This is of importance in providing an automatic adjustment of the disk into parallelism with the work whereby to adapt the disk and turntable for work of different thickness and for work which may be thicker on one side than on the other.

Located on bed-slide 30 is acircular disk-like turntable 3|] positioned in vertical alignment with the pressure disk 23 with which itcooperates to clamp plies 3|, 32, of the work fabric together in frictional engagement during the stitching operation, as seen clearly in Fig. l. The turntable 30 is seated within a recess 33 in the bed-slide and is 'pivotally secured thereto by a shouldered pivot screw 34 threaded into said bed-slide. Formed in the upper plane face of said turntable 30 is an annular groove 35 with which the annular raised rib portion 26 of the pressure disk cooperates to grip the fabric plies 31, 32 to increase the resistance against their movement relative to the turntable and to each other. This gripping action is illustrated best in Fig. 6 where the fabric plies 3| and 32 are shown snubbed around the rib portion 26 of the pressure disk to augment the normal frictional engagement of the fabric therewith.

In order that the usual vertical vibration of the presser-bar I caused by the feed-dog 5 will not lift the pressure-disk 23 out of engagement with the work during the stitching operation and thereby spoil the work or the accuracy of the path of stitches, the pressure-disc must have sufiicient vertical lost motion relative to the retainer loop 29 This amount of lost motion is adjusted so that when the presser-foot is at the top of its vertical movement due to the.

lift component of the feed, the retainer loop 29 is not elevated sufficiently to contact with the under side of the top flange collar of the hub portion 24 to raise the pressure disk 23. However, when the usual presser-lifter (not shown) is operated to raise the presser-foot 4, the retainer loop 29 is raised to engage the under side of the flange collar and lift the pressure disc upwards out of engagement with the work i which may then be removed or adjusted.

In operation, the presser-foot 4 is raised as usual for insertion of the work 3|, Fig. 3. This in turn causes bracket-arm 9 to rise and carries the body piece 13 into engagement with the collar 22 which is lifted, carrying with it the pivotpin [6. Further movement upwards of the presser-bar l raises the pressure disk 23, as described above, and allows the work 3! to be introduced into the position shown by dot-dash lines of Fig. 3. Next, the presser-bar is lowered to clamp the work between the feed-dog 5 and the presserfoot 4 at the stitching point and between the turntable 30 and the bed-slide 30 at the axis of rotation. Operation. of the feeding mechanism rotates the Work substantially about the axis of the pivot-pin and causes the stitches 36 to be formed in a circular path, as seen in Fig. 3.

When it is desired to apply a line of stitches in a circular path adjacent to and substantially concentric with a. central aperture, a modified turntable 31, as shown in Fig. 4 and in greater detail in Fig. 7 is used. This turntable 31 which is pivotally secured upon the surface of a bed- 'slide 38 by means of shouldered screw 39 has a raised hub portion 3! which may be passed through aperture 40 in work fabric 40 to fit within the cup-shaped pressure disk 23, and a flanged portion 31 between which portion and the rim portion 26 of the pressure disk is clamped in frictional engagement the work fabric 40 as shown in Fig. '7. An annular groove 42 is provided in the upper surface of the flange portion 31 to cooperate with the annular rib portion- 26 of the pressure disk to assist in gripping and holding the work 40, between the upper and lower clamping members. In the present case the effective area for frictional engagement between the work plies is insufficient because of the material taken out by the central aperture, and the additional gripping forces provided by the annular rib and groove combination are of special importance in preventing distortion of the material around the' aperture 40 It will be seenfrom the foregoing description that the raised hub portion 3T provides a means for readily and properly centering the apertured work fabric on the turntable. to insure the for-- mation of a circular line of stitches adjacent to and concentric with the edges of the aperture 4111 In this connection it is clear that by suitably adjusting the position 'of the angle bracket 9 within the slot 8' as well as by properly positioning the turntable 37 on the be'd slide '38 the diameter of the circular stitching path may be made to suit the particular work in hand.

We have found that for work involving circular stitching paths of small diameter the turntable and pressure disk combination prevents" wrinkling by preventing creeping of" one ply of the material over the other ply. However, for work of sufficient diameter of the circular path of stitches we have found it more convenient to dispense with both pressure disk andtu-rn'table and to employ the pivot-pin I B as a-spear-point with which to impale the Work and hold it pivotally the pivot-pin as is seen best in Fig. and in greater detail in Fig. 8. A bed-slide 43 is preferably provided with a complemental conical depression or seat 44 which cooperates with the pivot-pin point l6 to impale the work fabric and hold it against the throat-plate when the presser-foot is lowered for ordinary feeding. The pivot-pin may be adjusted for this operation by fixing the stop collar 22 at a higher point on the pivot-pin, thereby allowing the pivot-pin to impale the work 45 and extend partially into the seat 44, as most clearly seen in Fig. 8. The ready and convenient adaptability of this device for alternatively using either a pressure-disk and turntable or a spear-point and simple work support, provides great universality of application particularly including those cases in which penetration of the work cannot be tolerated.

From the foregoing description it will be perceived that we have provided a simple, rugged, inexpensive device which may be attached to existing sewing machines without changing the normal operation of said machines and which will adapt the machines for applying stitches to work material in circular paths including those in close proximity to and concentric with a central circular aperture in said work.

It is to be understood that our invention is not to be limited to the precise forms herein shown and described since it is susceptible of embodiment in various forms of construction all within the purview of the following claims.

Having thus set forth the nature of the invention, what we claim herein is:

1. In a sewing machine having stitch-forming and feeding mechanisms the combination with a presser-bar of a work-support, a lower turntable having an annular surface groove and carried by the work-support, an upper disk having a compresser-bar, a spring-biased pivot-pin formed with a pointed end and vertically slidable upon said arm, said disk having an axial socket recess within which the pivot-pin loosely fits and against the bottom wall of which the pointed end of said pivot-pin bears to urge said disk toward said turntable whereby to clamp the work therebetween.

2. A work-holding device for sewing machines comprising, a work-support, a presser-bar, sup porting means secured to said presser-bar, a pivot-pin spring-pressed downwardly and slidably carried by said supporting means for reciprocation along a vertical axis, a pressure disk containing an axial socket recess in which is freely and pivotally received one end of said pivot-pin, said disk having an annular surface rib and being releasably retained on said supporting means for limited vertical movement relative thereto, and a turntable freely pivoted on said work-support for rotation about said vertical axis and having a complemental annular surface groove for cooperation with said surface rib in said pressure disk to hold work therebetween in frictional engagement whereby said work may be clamped for free rotation about said vertical axis.

3. A work-holding device for sewing machines comprising, a work-support, a presser-bar, supporting means carried by said presser-bar, a pointed pivot-pin spring-pressed downwardly and slidably carried by said supporting means for reciprocation along a vertical axis, a pressure disk having an annular surface rib and containing an axial socket recess in which is freely and pivotally received the pointed end of said pivot-pin, releasable means for retaining said disk on said pivot-pin, and a turntable freely pivoted on said work-support for rotation about said vertical axis and having a complemental annular surface groove for cooperation with said surface rib in said pressure disk to hold work therebetween in frictional engagement whereby said work may be clamped for free rotation about said vertical axis.

4. A work-holding device for sewing machines comprising, a work-support, a presser-bar, supporting means secured to said presser-bar, a pointed pivot-pin spring-pressed downwardly and slidably carried by said supporting means for reciprocation along a vertical axis, a pressure disk containing an axial socket recess in which is freely and pivotally received the pointed end of said pivot-pin, means including a wire loop secured to said supporting means for retaining said disk on said pivot-pin, and a turntable freely pivoted on said work-support for rotation about said vertical axis and for cooperation with said pressure disk to hold work therebe tween in frictional engagement whereby said work may be clamped for rotation about said vertical axis.

5. A work-holding device for sewing machines comprising, a work-support, a presser-bar, a disklike turntable formed with an axially-raised hub portion, a pivot-screw extending through said hub-portion and threaded into said work-support pivotally to mount said turntable on said worksupport, an inverted cup-like member carried by said presser-bar and cooperative with said turntable to clamp the work therebetween, said member having an axial recess which receives the hub portion of said turntable, said hub providing means for properly centering apertured work in the device, with said member clamping the inner marginal portion of said apertured work against said turntable.

CHARLES A. KESSLER. HERMAN BITTER. 

